As environmentally friendly vehicles, electric vehicles, hybrid vehicles, fuel cell vehicles, etc., have received attention in recent years. On these vehicles, an electric motor that generates a traveling driving force and an energy storage apparatus that stores electrical energy to be supplied to the electric motor are mounted. On hybrid vehicles, an internal combustion engine is further mounted as a power source, in addition to the electric motor. On fuel cell vehicles, fuel cells are mounted as a direct-current power source for electric motor drive.
Vehicles are known that can directly charge an energy storage apparatus for electric motor drive mounted on such vehicles, from an ordinary household power source. For example, electrical energy is supplied to the energy storage apparatus from an ordinary household power source by connecting a commercial power outlet provided in a house to a charging inlet provided in the vehicle, by a charging cable. A vehicle that can directly charge an energy storage apparatus mounted on the vehicle from a power source external to the vehicle in the above-described manner is referred to as a “plug-in vehicle”.
Plug-in vehicle standards are established in the United States by “SAE Electric Vehicle Conductive Charge Coupler” (Non-Patent Document 1) and are established in Japan by “General Requirements for Electric Vehicle Conductive Charging System” (Non-Patent Document 2).
“SAE Electric Vehicle Conductive Charge Coupler” and “General Requirements for Electric Vehicle Conductive Charging System” define, as an example, a standard for control pilot. The control pilot is defined as a control line that connects a control circuit for EVSE (Electric Vehicle Supply Equipment) which supplies electrical energy to a vehicle from a premises wiring, to a ground unit of the vehicle through a control circuit on the vehicle side. Based on pilot signals communicated through the control line, a connection state of a charging cable, whether electrical energy can be supplied to the vehicle from a power source, a rated current of the EVSE, etc., are determined.
A connector of a charging cable is provided with a connection switch for detecting insertion of the connector into a charging inlet on the vehicle side. A PISW signal which is a state signal of the connection switch is inputted to a control apparatus that performs charging control of an energy storage apparatus mounted on the vehicle.
The control apparatus on the vehicle side includes a CPU that functions as a power control unit that controls a power source for vehicle system control; and a CPU that functions as a charging control unit that performs charging control of the energy storage apparatus.
The charging control unit controls the charging of the energy storage apparatus by determining whether it is a chargeable state, based on a charging mode signal inputted from the power control unit. The power control unit controls the power source for control by determining whether it is in the process of charging or charging has been completed, based on a charging completion signal inputted from the charging control unit.
Specifically, the power control unit is configured as follows. When the power control unit detects a rising edge (hereinafter, referred to as an “on edge”) of a PISW signal which is generated when the connector of the charging cable is inserted into the charging inlet on the vehicle side, the power control unit determines that the charging cable has been connected to the vehicle side, and thus, turns on a charging mode signal to activate the charging control unit. When the power control unit detects that a charging completion signal outputted from the charging control unit has been turned on, the power control unit determines that charging has been completed, and thus, turns off the charging mode signal.
Correspondingly, the charging control unit is configured as follows. When the charging mode signal is turned on by the power control unit, the charging control unit charges the energy storage apparatus mounted on the vehicle, with electrical energy supplied from an external power source through the charging cable. When the charging is completed, the charging control unit turns on the charging completion signal.